Regeneration of sulfur-poisoned raney nickel catalyst

ABSTRACT

Raney nickel catalysts which have been sulfur poisoned are regenerated by successive treatment first in an aqueous organic acid solution containing metal ions that form an insoluble sulfide in acid solutions, but which are soluble or decompose to soluble products and in an aqueous base solution. The catalyst is then separated and washed to remove traces of treating substances. The regenerated catalyst has an activity comparable to the freshly prepared catalyst.

United States Patent Pieters et al. 1 1 July 4, 1972 54] REGENERATION 0FSULFUR- 1,431,982 10/1922 Richter et al. ..252/413 POISONED RANEY NICKELCATALYST 3,165,478 1/1965 Hauschild et a1. ..252/413 2,289,784 7/1942Houghton ..252/413 [72] Inventors: W1ll1am Johan Meindert Pieters,Denville, 2,326,275 8/1943 Zehner v "252/477 0 John Fred, Oakmom, PM2,950,260 8/1960 Rosenbaum ..252/477 0 Bernard Anderson, AncasterOntario, 3,454,364 7/1969 Strum et 61...... ..252/466 1 Canada 3,480,53111/1969 Mulaskey ..252/466 1 .R.G &C.N Y k,N.Y. [73] Asslgnee w race 0cw or Primary E raminerDan1el E. Wyman [22] Filed: Oct. 21, 1970Assistant Examiner-P. E. Konopka [2]] App No 82 863 Attorney-Michael.l.McGreal and Kenneth E. Prince [57] ABSTRACT [52] 252/4 Raney nickelcatalysts which have been sulfur poisoned are 51] Int Cl "/76 ll/30 1H02 regenerated by successive treatment first in an aqueous or- Fie'ld4141412 01466 J ganic acid solution containing metal ions that form aninsolu- 260/667 666 ble sulfide in acid solutions, but which are solubleor decompose to soluble products and in an aqueous base solution. Thecatalyst is then separated and washed to remove traces of [56]References Cited treating substances. The regenerated catalyst has anactivity UNITED STA PATENTS comparable to the freshly prepared catalyst.

3,489,694 1/1970 Weidlich et al ..252/477 0 10 Claims, No DrawingsREGENERATION OF S-POISONIED RANEY NICKEL CATALYST BACKGROUND OF THEINVENTION This invention relates to a process for regenerating asulfurpoisoned, porous, finely-divided catalyst for use in, for example,a hydrogenation process. The catalyst is prepared by initially making analloy consisting essentially of nickel and aluminum, physically reducingthe alloy to a finely-divided state,

and chemically partially dissolving the aluminum from the alloy to forma porous finely-divided catalyst which comprises at least 2 weightpercent aluminum and the remainder a major part activated nickel and aminor part chemically-bonded oxygen. The process for regenerating thesulfur-poisoned catalyst involves admixing the sulfur-poisoned catalystin an aqueous solution containing an organic acid and metal ions thatform an insoluble sulfide in an acid solution. The pH of the admixtureis raised to between about 6.5 and about 8.0 by adding a base. By onetechnique, the pH of the admixture is first adjusted to 6.5-7.1 and in asecond step to about 7.2 and about 8.0. The liquid portion of theadmixture is removed to leave the catalyst portion, and the catalystportion is washed to produce a regenerated, porous, finely-dividedcatalyst.

Apparently sulfur poisoning involves the formation of nickel sulfide onthe catalyst surface, and regeneration is achieved by formation of adifferent non-poisoning sulfide, by reaction of the nickel sulfide withintroduced metal ions.

The catalysts of this invention may be employed in the hydrogenation ofcarbonyl-containing organic compounds to the correspondinghydroxy-containing compounds. They may also be employed in thehydrogenation of compounds containing aromatic unsaturation to formcycloaliphatic compounds, nitro groups to amino groups, or olefiniccompounds to saturated co-mpounds. The catalysts also may beadvantageously employed in certain dehydration, dehalogenation anddesulfurization reactions. 7

DETAILED DESCRIPTION OF THE INVENTION The Raney nickel catalyst can beprepared by any method known to the art. The alloy from which thecatalyst is prepared can contain from 30 to 60 weight percent nickel andfrom 40 to 70 weight percent aluminum. The examples give one method ofpreparing the catalyst. The fresh catalyst contains from 80 to 96 weightpercent nickel, from 2 to 12 weight percent aluminum, and the remainderis essentially chemically-bonded oxygen.

Bases which can be used to partially leach or chemically dissolve thealuminum from the alloy include sodium hydroxide, potassium hydroxide,sodium carbonate, calcium carbonate, tetramethyl ammonium hydroxide,etc.

The regeneration of the Raney nickel catalyst can be achieved by the useof a variety of organic acids. The organic acid must not have a highreactivity with the Raney material. The preferred organic acid istartaric acid.

Organic acids which can be used to regenerate the Raney nickel catalystinclude: saturated monocarboxylic aliphatic acids, e.g., formic acid,acetic acid, propionic acid, isovaleric acid, etc.; saturateddicarboxylic aliphatic acids, e.g., oxalic acid, maloric acid, succinicacid, glutaric acid, adipic acid, pimelic acid, etc.; saturatedtricarboxylic aliphatic acids, e.g., tricarballylic acid, etc.;hydroxy-substituted aliphatic acids, e.g., glycolic acid, lactic acid,or-hydroxybutyric acid, gluconic acid, tartronic acid, malic acid,tartaric acid, saccharic acid,

citric acid, etc.; and alicyclic acids, e.g., cyclopentane-carbox- Annheated rapidly to at least 40 C. and held at that temperature for atleast 5 minutes. The pH of the solution is then increased to betweenabout 6.5 and about 7.1 by the addition of a base. The base ispreferably in an aqueous solution, and the addition is preferably doneby means such as titration. The temperature can be maintained at theelevated level during the addition of the base.

Any base can be used to adjust the organic-treated catalystcontainingsolution to a pH between about 6.5 and about 7.1. The preferred base issodium hydroxide, but examples of suitable bases are potassiumhydroxide, sodium carbonate, ammonium hydroxide, calcium carbonate, etc.

Any base mentioned above can be used to raise the pH from between about6.5 and about 7.] to a value of about 7.2 to about 8 or above (up to ashigh as about 10). The preferred base is sodium hydroxide, and it ispreferably in an aqueous sOlution. Before the base is added, thetemperature of the admixture is lowered to a level below roomtemperature (about 0 The base treatments besides serving to activate theRaney nickel catalyst, also convert the insoluble metal sulfide producedin the organic acid treating step to a soluble condition so that it canbe removed from the catalyst-base solution admixture by decantation,filtration or some other known technique of separating a solid from aliquid. Following such a liquid removal step, the rejuvenated Raneynickel catalyst is washed, preferably with a dried alcohol, to removetraces of the treating solutions.

The activities in this application were determined for the hydrogenationof cyclohexene in ethanol at 30 C. with the hydrogen pressure maintainedat atmospheric pressure in a stirred micro-reactor. The reactorcontained 5 cc. ethanol and about 40 mg. catalyst, and 0.1 cc. ofcyclohexene was used. The hydrogenation was followed by measuring theuptake of hydrogen. Activities are based on the slope of the hydrogenconsumption time curve at a conversion of 50 weight percent of thecyclohexene, divided by the weight of catalyst, but are reported here ona relative basis.

As used herein, the term room temperature is defined as a temperaturebetween 60 F. and F.

Weight percent or percent by weight as used throughout this application,unless otherwise specifically stated, is defined conventionally as gramsper hundred grams of total composition (dry basis).

The following examples illustrate this invention. All percentages andparts therein are by weight, unless otherwise stated.

EXAMPLE I A nickel-aluminum alloy was prepared by adding 200 gm. ofaluminum shot and 200 gm. of nickel shot to a graphite crucible. Theoptimum aluminum and nickel shot diameter was about V4 inch; shot lessthan A inch was diflicult to stir, and shot greater than inch resultedin a very large exotherrn. The crucible was placed in a furnace at about1,100 C. Cooling caused by the crucible as well as heat loss caused byopening the fumace door, lowered the temperature to about l,000 C. Thecrucible was removed from the furnace after about 15 minutes, at whichtime the fumace temperature was l,075-l ,100 C. Immediately afierremoval from the furnace, the crucible contents were stirred with acarbon rod; no attempt was made to preheat the rod before stirring.After vigorous stirring for 30 seconds, the contents gradually turnedred, and then metal solution took place, resulting in a white hot melt.The melt was stirred for an additional 15 seconds. The resultant alloycontained about 50 weight percent A] and about 50 weight percent Ni.

The nickel-aluminum alloy was easily crushed to jagged, irregularlyshaped pieces about inch X Va inch in a jaw crusher. The pieces are thenreduced to a fine powder (-200 mesh, U. S. Sieve Series), using a ballmill with 6 inch steel balls. The catalyst was prepared and activated byadding the 200 mesh alloy powder to a 1 liter resin kettle flask alongwith 100 ml. of tap water. Then 100 ml. of 40 percent NaOH solution wasslowly added. After the addition of the first 10 ml. of NaOH, hydrogenevolved vigOrously, and the solution temperature rose rapidly to 90l00C. The first 50 ml. were added in -10 ml. increments over a period of 5minutes, after which the remaining 50 ml. were added rapidly. A magneticstirrer was used to keep the flask contents agitated. The total Hevolved was measured, using a wet test meter. The flask was heated tomaintain the contents at a reflux temperature of about 107 C. Theleaching (activation) time was 2 hours. After leaching (activation), thecatalyst was washed with tap water by filling and decanting the flask 6times. The porous Raney nickel catalyst contained 90 weight percent Ni,3.1 weight percent Al, and the balance being oxygen. The catalyst had anactivity of 240.

EXAMPLE 2 1.0 gm. of the freshly prepared Raney nickel of Example 1 wasstirred in ethanol containing 0.01 cc. CS After this treatment, thecatalyst activity was 144. Two portions of the poisoned catalyst werethen treated each with a solution of tartaric acid containing somestannous tartrate for minutes at 50 C. (The tartaric acid solution wasprepared by heating finely divided tin in an aqueous solution of 1 gm.tartaric acid in 50 cc. water for 3 hours. The solution was poured fromthe undissolved tin and used in the regenerations.) The solution wasneutralized with NaOH, cooled to 0 C., and the pH carefully adjusted to7.5 using NaOH. The catalyst was removed from the solution and washedwith absolute ethanol. The two samples had activities of 200 and 210,respectively.

EXAMPLE 3 Example 2 was repeated, except that the fresh catalyst waspoisoned with 0.013 cc. CS per gram of catalyst to an activity of 104.The two regenerated samples had activities of 200 and 215, respectively.

EXAMPLE 4 Example 2 was repeated, except that the tartaric acid wasreplaced with lactic acid. A regenerated catalyst was obtained.

EXAMPLE 5 Example 2 was repeated, except that the tartaric acid wasreplaced with acetic acid. A regenerated catalyst was obtained.

EXAMPLE 6 Example 2 was repeated, except that the tartaric acid wasreplaced with formic acid. A regenerated catalyst was ob tained.

EXAMPLE 7 Example 2 was repeated, except that the sodium hydroxide usedfor leaching and neutralizing was replaced with sodium carbonate. Aregenerated catalyst was obtained.

EXAMPLE 8 Example 2 was repeated, except that the sodium hydroxide usedfor leaching and neutralizing was replaced with potassium hydroxide. Aregenerated catalyst was obtained.

EXAMPLE 9 Example 2 was repeated, except that the solution of tartaricacid contained lead ions instead of stannous tartrate. A regeneratedcatalyst was obtained.

As used in this application, dried alcohol means an alcohol having up toabout a 4-7 percent water content. Absolute ethanol is an ethanol havinga 1 percent or less water content.

What is claimed is:

l. A process for regenerating sulfur-poisoned, porous, finely-dividedcatalyst, said catalyst having been prepared by preparing an alloyconsisting essentially of nickel and aluminum, physically reducing saidalloy to a finely-divided state, and chemically partially dissolvingsaid aluminum from said alloy to form an active porous finely-dividedcatalyst, which comprises:

a. admixing said sulfur-poisoned catalyst with an aqueous solutioncontaining an organic carboxylic acid from the group consisting ofsaturated, hydroxy-substituted aliphatic, and alicyclic, and metal ionsfrom the group consisting of stannous ions and lead ions that form aninsoluble sulfide in an acid solution whereby a solid metal sulfidecompound is formed;

b. adding an aqueous solution of a base from the group consisting ofsodium hydroxide, potassium hydroxide, sodium carbonate, ammoniumhydroxide, and calcium hydroxide to raise the pH of this admixture tobetween about 6.5 and about 8.00, thereby solubilizing said metalsulfide compound;

0. removing the liquid portion of the admixture, said liquid portioncontaining said metal sulfide compound; and

d. washing a remaining solid portion, producing a regenerated, porous,finely-divided catalyst.

2. A process as in claim 1 wherein the pH of said admixture is firstraised to about 6.5 to 7.1, and then in a second step raised to betweenabout 7.2 and 8.0.

3. A process as described in claim 1 wherein said organic acid istartaric acid and said metal ion in the stannous ion.

4. A process as described in claim 1 wherein after said admixing of step(a), the temperature of the resulting admixture is raised to at leastabout 40 C.

5. A process as in claim 1 wherein said organic acid is tartaric acidand said metal ions are lead ions.

6. A process as in claim 1 wherein said organic acid is lactic acid andsaid metal ions are stannous ions.

7. A process as in claim 1 wherein said organic acid is acetic acid andsaid metal ions are stannous ions.

8. A process as in claim 1 wherein said organic acid is formic acid andsaid metal ions are stannous ions.

9. A process as in claim 1 wherein said base is selected from the groupconsisting of sodium hydroxide, potassium hydroxide and sodiumcarbonate.

10. A process as in claim 9 wherein said base is sodium hydroxide.

t I t

2. A process as in claim 1 wherein the pH of said admixture is firstraised to about 6.5 to 7.1, and then in a second step raised to betweenabout 7.2 and 8.0.
 3. A process as described in claim 1 wherein saidorganic acid is tartaric acid and said metal ion in the stannous ion. 4.A process as described in claim 1 wherein after said admixing of step(a), the temperature of the resulting admixture is raised to at leastabout 40* C.
 5. A process as in claim 1 wherein said organic acid istartaric acid and said metal ions are lead ions.
 6. A process as inclaim 1 wherein said organic acid is lactic acid and said metal ions arestannous ions.
 7. A process as in claim 1 wherein said organic acid isacetic acid and said metal ions are stannous ions.
 8. A process as inclaim 1 wherein said organic acid is formic acid and said metal ions arestannous ions.
 9. A process as in claim 1 wherein said base is selectedfrom the group consisting of sodium hydroxide, potassium hydroxide andsodium carbonate.
 10. A process as in claim 9 wherein said base issodium hydroxide.